Water-resistant, monodispersed and stably luminescent CsPbBr₃/CsPb₂Br₅ core-shell-like structure lead halide...

Lead halide perovskite materials are thriving in optoelectronic applications due to their excellent properties, while their instability due to the fact that they are easily hydrolyzed is still a bottleneck for their potential application. In this work, water-resistant, monodispersed and stably luminescent cesium lead bromine perovskite nanocrystals coated with CsPb₂Br₅ were obtained using a modified non-stoichiometric solution-phase method. CsPb₂Br₅ 2D layers were coated on the surface of CsPbBr₃ nanocrystals and formed a core-shell-like structure in the synthetic processes. The stability of the luminescence of the CsPbBr₃ nanocrystals in water and ethanol atmosphere was greatly enhanced by the photoluminescence-inactive CsPb₂Br₅ coating with a wide bandgap. The water-stable enhanced nanocrystals are suitable for long-term stable optoelectronic applications in the atmosphere.